1. Field of the Invention
This invention relates to a gaseous phase method accumulated film manufacturing apparatus, and more particularly to a gaseous phase method accumulated film manufacturing apparatus for forming a photoconductive film, a semiconductor film, an inorganic insulating film, an organic resin film or the like on a substrate by the plasma CVD method and which is capable of manufacturing various kinds of products by one production line.
2. Description of the Prior Art
As typical ones of apparatuses for causing a photoconductive film, a semiconductor film, an inorganic insulating film, an organic resin film or the like to be accumulated on a substrate by the plasma CVD method, mention may be made of so-called coaxial cylinder type and parallel flat plate type accumulated film manufacturing apparatuses.
The coaxial cylinder type accumulated film manufacturing apparatus is an apparatus which is capable of accumulating, for example, a non-crystalloid silicon photosensitive film on a cylindrical metal substrate formed of aluminum or the like and forming a photosensitive drum for electrophotography, and the construction thereof is such that the cylindrical substrate and a cylindrical cathode electrode sharing the center axis with the substrate are disposed so that glow discharge is caused to occur therebetween.
An example of such apparatus will hereinafter be described by reference to FIG. 2 of the accompanying drawings which is a longitudinal cross-sectional view thereof. Reference numeral 21 designates a cylindrical cathode electrode which shares the center axis with a cylindrical substrate (anode electrode) 22. Reference numeral 23 denotes doughnut-shaped electric insulators, reference numeral 24 designates a vacuum chamber lid, reference numeral 25 denotes a high-frequency power source, reference numeral 26 designates a raw material gas discharging pipe, reference numeral 27 denotes a vacuum exhaust pipe, reference numeral 28 designates a heater for heating the substrate, reference numeral 29 denotes a substrate rotating mechanism, and reference numeral 30 designates the each.
In this apparatus, one substrate is disposed for one reaction furnace, and this leads to an advantage that the adjustment of the distribution of the non-crystalloid silicon accumulated film is easy, for example, by the flow or distribution of gas and moreover the apparatus is excellent in stability of discharge.
On the other hand, the parallel flat plate type accumulated film manufacturing apparatus uses, as a pair of opposed electrodes, flat plates disposed parallel to each other, instead of the above-described two cylinders sharing the center axis, and has a structure as shown in the transverse cross-sectional view of FIG. 3 of the accompanying drawings.
In this example, glow discharge is caused to occur between a planar cathode electrode 31 and a planar substrate (anode electrode) 32, whereby an accumulated film can be formed on the substrate 32.
In these apparatuses, the spacing between the pair of opposed electrodes is in a close relation with the intensity of glow discharge and forms an important factor which governs the film thickness distribution and film characteristic of the accumulated film, and it is preferable that said spacing be kept at a proper predetermined distance to form an accumulated film of good quality.
Generally, the characteristic of the accumulated film and the size of the substrate on which the accumulated film is formed differ depending on for what usage the product after the formation of the accumulated film is used. However, where an accumulated film is to be formed on a substrate by the use of the apparatus as described above, if the apparatus is of the coaxial cylinder type, the spacing between the cylindrical substrate and the cathode electrode must be made constant as previously described, and in a reaction furnace wherein a cathode electrode of a predetermined size is provided, if a substrate different in size, particularly, in outer diameter, is disposed in the reaction furnace, the distance between the substrate and the cathode electrode does not become a predetermined distance and good film formation cannot be carried out and therefore, it has been impossible to apply substrates different in outer diameter to an apparatus.
Also, in the case of the parallel flat plate type apparatus, it is necessary that at least the cathode electrode be larger than the substrate, and further taking the matching or the like of these into account, it has been difficult to apply substrates of various shapes to a reaction furnace in which a cathode electrode of a predetermined shape is provided.
Accordingly, where accumulated films are to be mass-produced by the use of the apparatus as described above, the apparatus has unavoidably been a line exclusively for use in accord with the size of the substrate and the desired characteristic of the formed accumulated film, and above all, it has been impossible to produce numerous kinds of products by freely flowing substrates different in size.